This invention relates to outdoor street lighting or area lighting luminaires and more particularly to a novel lamp socket mounting and adjusting assembly for selectively adjusting the focal point and focal axis tilt of a lamp employed in such a luminaire.
In an outdoor street lighting or area lighting luminaire, it is desirable to be able to change the light distribution pattern of the luminaire without resorting to changing the reflector design or the light distribution pattern by utilizing a plurality of different refractors. One way to accomplish the modification of the light distribution pattern produced by a luminaire is to change the focal point or focal axis of the light source with respect to the remainder of the optical cavity.
In the past, the position of the light source with respect to the reflector and refractor has been adjusted by various types of socket mounting assemblies. Some examples of variety adjustable socket mounting assemblies for use in street lighting luminaires are disclosed in U.S. Pat. No. 3,299,263 to Bjontegard, U.S. Pat. No. 3,348,035 to Franklin et al. and U.S. Pat. No. 3,705,301 also to Franklin et al.
Some of the drawbacks of these earlier lamp socket adjustment mechanisms are the fact that in some instances, they must be disassembled and parts reversed in order to provide for the full scope of adjustability necessary to provide the various kinds of different light distribution patterns. Others, of the prior art lamp socket adjustment assemblies are constructed such that the adjusting screws and movable parts are difficult to gain access to because of their locations on the side of the adjustment mechanisms. If the lamp socket assembly is lowered to a point below the sidewall of the housing to provide access to the adjusting screws, then the luminaire must have a substantially greater vertical dimension giving a bulky less streamlined appearance. Additionally, it is important that the indicia indicating the position of the lamp socket with respect to the optical cavity are easily readable by the person making the final adjustment of the lamp socket mounting assembly.